6.2L Buildup

Turning an old 20-Something GM Diesel Into a Modern Power Puller

They are plentiful, they are durable, and they are cheap. In addition, they're simple and economical. Those five factors are what make the venerable 6.2L Chevrolet diesel a very popular builder these days, especially if you are planning on plopping one under the hood of an older 1/2-ton pickup or SUV in place of a gas V-8. The engines were a mainstay in the '82-'93 GM light-duty truck line under the hoods of Chevrolet and GMC pickups, Suburbans, and fullsize vans. The 6.2L was replaced in 1994 by the 6.5L, which was subsequently replaced by the Duramax 6600 in 2001.

This is the '82 C1500 that donated its 6.2L to our cause. The engine wasn't running because the owner had melted off the glow plug's tips and couldn't figure out how to remove them without removing the heads. The engine had less than 200,000 miles on it. We bought the whole truck for $500.

This is the '82 C1500 that donated its 6.2L to our cause. The engine wasn't running becaus

Finding a Good DonorEven though they have been out of production for nearly a decade, there are still a lot of 6.2Ls on the road-and countless others sitting idle that could easily be put back on the road. What that means to the diesel-loving do-it-yourselfer is if you are in need of a good diesel engine for your older pickup or SUV, you can find the 6.2Ls with little effort. They are lying around everywhere you look. Literally. If you spot an old, beat-up GM pickup or big van sitting beside a barn, wedged in the farthest row of junkyard dogs, or serving as a trellis for a growth of blackberries, it probably has a 6.2L diesel under the hood. These parts trucks are fine for just that-parts. But, the ones you probably want to check out for rebuilding the diesel are not those rusting away, but rather those listed in the used vehicles section of any newspaper. You know the ones-those old GM diesel pickups that still run and can be had for less than the price of a set of new tires, or better yet, are being given away.

Many of these bargains are parked either because the truck around the engine has fallen apart or the engine itself, as the owner sees it, was nearing the end of its life and the owner simply moved on to other modes of transportation rather than deal with the cost of rebuilding either the truck, the diesel, or both. Believe it or not, most of the time, these trucks are being parted with because they will not start in cold weather because of a problem with the glow plugs or bad relays. If the truck isn't rusted completely into the ground and the engine hasn't been sitting under water, one person's junker becomes a diesel builder's treasure.

Builder/Buyer BewareThe caveat to this entire 6.2L rebuilding process rests on one thing: the year of the engine you use as your base. Heed this advice: If the engine you are contemplating as the builder is pre-'88, find a newer engine for the best performance and reliability from the rebuild at the cheapest price. As Warren Spears, the owner and co-builder of this project says, "If you raise the hood of the donor vehicle and you don't see a serpentine belt system, rapidly close the hood, thank the person for showing you the vehicle, and quickly walk away." We found that out the hard way on this rebuild. Our junkyard '82 C1500 diesel pickup cost $500. Warren sold the truck for parts, sans engine, for $400, so the C-model 6.2L ended up costing $100. However, as much of a bargain that was, it cost an additional $1,900 to upgrade the engine to the higher-performance, more reliable J-model by the time we bought reworked, later-model ('90-'92) heads for $900, the newer-model rocker arm assemblies for $200, and the brackets and drive accessories to convert the engine to the serpentine-belt drive for $800. That doesn't include the aggravation and time involved tracking down the better parts and figuring out how to upgrade the engine to the more reliable, later-style 6.2L. "We'd had been far better off spending $2,000 on a '93 model that had a good body and the latest version of the 6.2L," reminisces Spears. "But, hindsight, as they say, is always 20/20." Thankfully, Warren had several aces-in-the-hole. One was at the local Chevy dealer. Daryl "Woody" Woods, a superb parts counterman at DeRussy Chevrolet in Bay St. Louis, Mississippi, took the time and knew where to find all the parts to make the upgrade. The other great help in this rebuild was our local O'Reilly Auto Parts store in Long Beach, Mississippi, where Jason Carey, the store's manager, provided similar parts assistance, including providing a Federal Mogul Premium Master Engine rebuild kit-and a number of other must-have items that cropped up along the way.

Without those two guys, "The Diesel Page 6.2L Diesel Engine" reference manual, and a copy of Haynes Diesel Engine Repair Manual, undertaking a 6.2L rebuild for the first time would have been a lot more "interesting." The Diesel Page manual is a must-read before you undertake a 6.2L rebuild. Of course, if the engine you plan on giving new life to is an '82-'88, and it's still running, stay the course and rebuild it back to stock; the 25 extra ponies and 45 lb-ft of additional torque gained from the later-model, naturally-aspirated 6.2L might not be worth the time or cost needed to make the upgrade.

Rebuilding For PowerRebuilding the 6.2L diesel is a comparatively cheap way to have reliable and capable diesel power. Instead of paying $6,500 for a crate 6.5L short-block, you can rebuild a 6.2L and kit it with a Banks turbo for about $4,500. As a note of interest, back in 1989, GM chose Banks as the 6.2L dealer-installed turbo option, and remained so until GM released its own 6.5L turbodiesel. This ultimate upgrade for the venerable 6.2L workhorses provides as much as 60-plus hp and 115-plus lb-ft of torque, plus 10 percent better fuel economy according to Banks.

Of course, we wanted everything we could get out of the ancient '82 we bought. That meant a lot of new parts and special attention to details to give it new life. In addition to the typical engine rebuild parts, we stepped up the power quotient on our builder by installing a Banks Sidewinder turbo kit-a dealer option GM offered in the latter days of the 6.2L. The $2,100 Banks kit includes everything from the Banks Ram-Air intake with cast air-filter housing to the Sidewinder turbo with turbocharger exhaust manifold, pressure-chamber-plenum boost tube, special radiator hose, and crankcase-vent duct. It also includes a complete 3-inch stainless exhaust system with a Dynaflow muffler.

Speaking of the power from a rebuilt 6.2L, we ran our "new" Banks' turbo'd engine on the dyno at Vanderley Racing Engines in Lyman, Mississippi, not far from where Karl Hagar and Warren Spears did the overhaul. Here's what we found: The original '82 6.2L delivered 130 hp and 240 lb-ft torque. Our "new" 6.2L delivered 58 hp more than the stock engine did and 110 lb-ft of torque between 1,100 and 1,800 rpm, and 40 hp and 85 lb-ft more power at 2,800. That puts our builder engine in the same power range as the 6.5 turbo found in today's GM heavy-duty pickups.

So, as you can see, the end result of a 6.2L GM rebuild is a stout, reliable, fuel-efficient diesel that runs as good as or better than the popular 6.5L turbodiesel. We expect to get a decade or more of service from this one-and a lot of raised eyebrows when we open the hood to show off how fine a 24-year-old turbodiesel looks. You should see similar results.

The year of the truck and a look under the hood should have been our first clues this wasn't the right engine to begin a rebuild. It wasn't the leaves in the intake or corrosion on the valve covers that make this a bad choice-it's the lack of a serpentine belt drive that distinguishes between the good years and the so-so 6.2Ls. But, we went ahead anyway.

The year of the truck and a look under the hood should have been our first clues this wasn

A word of caution that will save you time in the rebuild process. When you go to remove the injector pump and lines for the rebuild be very, very careful not to bend them in any way. If you do, plan on spending hours reshaping them during the rebuild. The original owner had yanked this engine's injector lines off without care or concern putting them back on.

A word of caution that will save you time in the rebuild process. When you go to remove th

The original cam showed signs of worn lobes. It was still useable in a pinch, but the Federal Mogul Master Rebuild Kit comes with a new one so we chucked the old.

The original cam showed signs of worn lobes. It was still useable in a pinch, but the Fede

A critical aspect of the rebuild is making sure the block, crank, and heads are fit to reuse. A good hot-dip and magnafluxing will reveal any problem areas. Our parts checked out fine, but we set the old-style heads aside and used a pair of rebuilt late-model '92 heads. Also, close inspection of the crank is critical. Not only does it need to be within close tolerances, but it is critical that the bearing surfaces be flawless. Although GM recommends not surfacing the crank, there are no new ones available and other sources, such as The Diesel Page, say doing so does not affect its strength or durability. Our crank had some watermarks on the main journals that required a 0.010-inch grinding and a special set of oversized Federal Mogul bearings.

A critical aspect of the rebuild is making sure the block, crank, and heads are fit to reu

Banks' Sidewinder Turbo Kit includes everything needed to convert the 6.2L over to turbo power. We had a lot of the pieces powdercoated yellow to match the truck that the "new" engine will be going into within the next few months.

Banks' Sidewinder Turbo Kit includes everything needed to convert the 6.2L over to turbo p

One of the optional upgrades in the rebuild is converting the old timing chain assembly to the gear-drive. The Diesel Service Group is the only one offering this kit, which it calls the Phazer Kit (PET 62GD, $325). DSG says, "The timing chain used on the 6.2L and 6.5L engines cannot withstand the continuous shock loads transmitted to it via the injection pump, which can reach peak pressures in excess of 12,000 psi. These shock loads cause the chain to wear, and the resulting vibration can lead to several expensive problems, such as broken main bearing castings, sheared crankshaft keys, broken harmonic balancers, unstable timing, and poor performance."

One of the optional upgrades in the rebuild is converting the old timing chain assembly to

Another performance/reliability upgrade we did was to install DSG's Stud Girdle Kit (DSG 65SG-12mm Kit, $145). DSG says, "The 6.2/6.5 engine block has a bad history of cracking from the outer main bearing bolt holes up through the cylinders causing catastrophic engine failures. The DSG Stud Girdle Kit avoids this common problem by replacing the outer main bearing bolts on the three middle webs with high-tensile studs and nuts. By joining these webs together the studs eliminate the spreading force put on the block while torquing the main caps."

Another performance/reliability upgrade we did was to install DSG's Stud Girdle Kit (DSG 6

When installing the new cam, we made sure the soft plug in the rear of the block was not pressed in too far. If it is, the cam will not turn when the retainer is bolted into place and the geardrive installed. Some machine shops don't check this before you get the refurbished block back.

When installing the new cam, we made sure the soft plug in the rear of the block was not p

You can't overuse gasket sealer on the 6.2L rebuild, especially the pre-'85 model blocks that used the two-piece rear main seal. This is another reason to start with a '88-and-later block.

It is always best when rebuilding any diesel that you use a rebuilt (exchange) injector pump and have the injectors tested (replace with rebuilt ones, if bad). It's hard enough to get to them out of the truck, let alone in. We had our pump tweaked about 10 percent above stock to accommodate the Banks turbo system-per Banks' instructions. A rebuilt pump runs about $325.

It is always best when rebuilding any diesel that you use a rebuilt (exchange) injector pu

A good rule of thumb is to use Never-Seez on the injectors. If you don't, and they need to be replaced, you might not get them out. However, do not use anything on the glow plugs that keep them from making contact with the block!

A good rule of thumb is to use Never-Seez on the injectors. If you don't, and they need to

You can save yourself a lot of money during the rebuild process by using 1/8-inch fuel line hose instead of paying $7 apiece for the GM injector return line hoses and another $2.65 each for the spring clips that hold the hoses to the injectors. We bought the hose in bulk from O'Reillys all for $17-and no clamps were necessary.

You can save yourself a lot of money during the rebuild process by using 1/8-inch fuel lin

Not only do we recommend using copious amount of oil and white grease on all the moving parts, replacing all main cap (GM#14077192; GM#23502575) and head bolts (GM#14077193) with genuine GM replacement parts is also highly recommended. This adds about $275 to the cost of the rebuild, but ensures there are not any stretched bolts holding the engine together. The head bolts are under a lot of stress, engine running or not.

Not only do we recommend using copious amount of oil and white grease on all the moving pa

The Federal Mogul Premium Master Rebuild Kit (#MKP6084A) we sourced through O'Reilly Auto Parts included everything you need to rebuild the 6.2L from gaskets to pistons-sans the wristpin bushings, which we bought when installed by the machine shop.

The early model '82-'84 6.2Ls used a gear-driven oil pump with a vacuum pump sitting high atop the drive assembly (left). We wanted to keep this engine as clean looking as possible, so we converted it to serpentine drive and in doing so eliminated the cumbersome vacuum pump. We were left with two oil pump drive choices-with or without speed sensor. We chose the former so we could have cruise control.

The early model '82-'84 6.2Ls used a gear-driven oil pump with a vacuum pump sitting high

If you are rebuilding an '85-and-later "J-model" engine, you should have the heads reworked. If you have a pre-'85 engine and want the better flowing, higher horsepower heads found in the newer years, good luck. The "J-model" heads are virtually non-existent from GM and almost as rare in the rebuild world. We were lucky to find this set of rebuilt heads for $900.

If you are rebuilding an '85-and-later "J-model" engine, you should have the heads reworke

Another reason to start with at least a '85 6.2L is the rocker arm assemblies. The old versions (top) didn't oil effectively resulting in badly worn bushings and shafts. The newer J-model version solved that problem. We put in new rocker arm assemblies from O'Reilly Auto Parts, which added about $112 for the rocker arms and $50 for the shafts.

Another reason to start with at least a '85 6.2L is the rocker arm assemblies. The old ver

These little plastic push-in rocker arm retainers (GM#23500076) are non-reusable. GM sells them in packets of 20 for about $30.

One item that is easy to overlook is the oil pump shaft. We made sure the old one was straight as they tend to bend. To be safe, we used a new one from GM that has a tab to keep the shaft from bottoming out in the pump.

One item that is easy to overlook is the oil pump shaft. We made sure the old one was stra

We carefully inspected the water pump assembly during the tear-down process. You want to use a brand-new water pump, since they are a pain to replace if something goes wrong. We also had to upgrade to the newest water pump mounting plate (GM#12562659) and install a GM-only 1-inch pipe-style bypass hose adapter (GM#10183956).

We carefully inspected the water pump assembly during the tear-down process. You want to u

Optimum glow plug operation and longevity are big concerns in any diesel, no more so than the 6.2L with a turbo, since they are really hard to access/replace. So, we deferred to the expertise and suggestions of Jim Bigley, editor of The Diesel Page manual and installed ACDelco #80G (PN 12563554). These glow plugs are said to last the longest of any variety available.

Optimum glow plug operation and longevity are big concerns in any diesel, no more so than

A huge time-saver is bagging and marking every part that is removed from the truck and engine during the disassembly process. This can't be overstated. It's amazing how much you forget when you start trying to put it all back together again.

A huge time-saver is bagging and marking every part that is removed from the truck and eng

We made sure to lay down a thick bead of gasket sealant along the sharp edge, where the front of the oil pan meets the timing cover and block. This is a prime area of oil leakage. Our motto is "Do it now or redo it later."

We made sure to lay down a thick bead of gasket sealant along the sharp edge, where the fr

The Master Rebuild kit comes with two sets of intake gaskets. We used the non-EGR gaskets (right) that have the center opening of the exhaust gasket covered up with a metallic gold-colored material. We made sure to use the proper one for our application.

The Master Rebuild kit comes with two sets of intake gaskets. We used the non-EGR gaskets

We installed a non-EGR intake manifold similar to those found on the military 6.2Ls, which is essentially reverting to a heavy-duty emissions engine. (If you live in an emissions-controlled area, Banks will send a light-duty emissions kit.) If you are worried the parts of the EGR system blocking the intake will rob power, don't worry-intake restriction becomes a moot point with forced induction system. We already had the "cleaner" manifold, so we used it.

We installed a non-EGR intake manifold similar to those found on the military 6.2Ls, which

It is very advisable to install a new harmonic balancer (GM#14022671) along with a new crankshaft pulley (O'Reilly #DOR594-037) on serpentine belt drive models because diesel experts say these two items are really the weakest points in the 6.2L. A bad harmonic balancer is a quick road to a broken crankshaft, and a broken pulley will result in direct contact with the harmonic damper bolts, making it sound like the engine threw a rod.

It is very advisable to install a new harmonic balancer (GM#14022671) along with a new cra

We took great care removing the old injector pump and lines so they were not bent. If they are bent, as ours were, it'll take you hours of aggravation getting them back in proper alignment.

We took great care removing the old injector pump and lines so they were not bent. If they

Another major time-saver is keeping the old pump and injector lines intact, then removing the lines one at a time so you know where each goes on the new pump in relation to the engine.

Another major time-saver is keeping the old pump and injector lines intact, then removing

We wanted our rebuilt engine to turn a few heads on the street and while the hood was up. Gulf Coast Powder Coating to have all the non-high heat sensitive parts colored to match the truck the engine is going to reside in.

We wanted our rebuilt engine to turn a few heads on the street and while the hood was up.

We found this "military" version of the anti-depression valve (CDR) at a salvage yard. It worked great on our civilian engine. The stock CDR usually mounts right into the top of the passenger-side valve cover, where as this one sits between the intake and valve covers, tidying up the entire look.

We found this "military" version of the anti-depression valve (CDR) at a salvage yard. It

When we used the lower profile "military" non-EGR intake manifold, it was be necessary to fabricate a spacer so the Banks plenum would align properly with the intake from the turbo. We used-don't laugh-a 1-inch-tall section from a 6-inch PVC sewer pipe coupling and sprayed it with high-heat silver. It worked great.

When we used the lower profile "military" non-EGR intake manifold, it was be necessary to

Our ace diesel rebuilder, Karl Hager, installs the special Banks exhaust manifold that accommodates the turbo. The Banks Sidewinder Turbo kit is very complete and instructions detailed. Mounting the kit on the engine while it's sitting on an engine stand cuts, what could be a 20-hour DIY'er installation in the truck, down to 2 hours.

Aluminum heat shield hides the neat little Banks turbo, but it's a necessity in the tight confines and close proximity to the injector lines and glow plug wiring. Everything in the Banks kit fits without modification of any type and exactly as described in the instructions.

Aluminum heat shield hides the neat little Banks turbo, but it's a necessity in the tight

Our rejuvenated "High-Output" 6.2L is ready for the accessories and then off to the dyno. A little powdercoating for color gives the new engine just the right look to go with its performance gained from the rebuild and addition of the Banks Sidewinder turbo kit.

I had a 6.2 that I put over 200k miles on. About the only thing I had to do to it was replace glow plugs occasionally, and change the oil. It was reliable, and you could work on it yourself. It was also a dog.

Calvin only reason people say that the Powerstrokes are junk after the 7.3L is cause everyone thought they could work them to death with out doing maintenance to them. Using the wrong oils, fluids, after market filters, tunes....if ya did a few minor things and didn't use a tune these engines would last a long time.

The old 6.2 and 6.5 were seriously the worst diesel motors built. I've worked on several and not only are they a nightmare, the parts are getting more scarce as well. The thing I never understood about them is why didn't they have an I/C. Would've been beneficial.

No they don't. Lol go research something. Literally everything you just said is wrong. The duramax is built ENTIRELY in moraine ohio by DMAX corp. which is owned by GM. The only thing Isuzu ever did was CO-DESIGN the motor with GM. I swear you people are idiots.

I got a 84 blazer with 1 ton axles on 44" tires 6.2 around 450k still runs fine.. have a 93 dodge 1 ton 4x4 cummins its broken.. at 253k had a 95 dodge cummind blew motor at 237k yea 6.2 reliable just not most power